BACKGROUND Pancratistatin, a natural compound extracted from Hymenocallis littoralis, can selectively induce apoptosis in several cancer cell lines. In this ex vivo study, we evaluated the effect of pancratistatin on peripheral blood mononuclear cells obtained from 15 leukemia patients prior to clinical intervention of newly diagnosed patients, as well as others of different ages in relapse and at various disease progression states. RESULTS Mononuclear cells from healthy volunteers and leukemia patients were exposed to 1 microM pancratistatin for up to 48 h. Irrespective of leukemia type, pancratistatin induced apoptosis in the leukemic samples, with minimal effects on non-cancerous peripheral blood mononuclear control cells. CONCLUSIONS Our results show that pancratistatin is an effective and selective anti-cancer agent with potential for advancement to clinical trials.